Establishing the synthesis/structure relationship of molybdenum/lead chalcogenide quantum dot mesocrystals

在这个由材料研究部固体和材料化学计划支持的项目中，康奈尔大学的Tobias Hanrath教授将探索一类将纳米颗粒与二维(2D)材料相结合的新型材料的合成-结构关系。通过类比岩石-剪刀-布的游戏，研究人员将使用胶体纳米颗粒(即岩石)来在纳米颗粒的特定部分形成硫化钼薄片(即纸)。与剪刀不同，所提出的合成方法利用定义良好的纳米颗粒形状(例如，截断的立方体)来定义颗粒-片状复合材料的几何形状。该项目除了创造具有科学和社会重要性的新知识外，还将产生重大的更广泛的影响，潜在地导致具有独特光学、电子和催化性能的新的纳米结构复合材料的开发。研究生将在材料制造和表征方法的结合中接受广泛的培训和经验，以调查、理解和预测复合纳米结构的形成。外展和教育与科学工作紧密结合。研究人员将开发一个“回到未来”的研讨会，通过发展他们对其特定研究领域的未来的愿景，更广泛的技术影响，以及他们个人在实现这一未来方面的角色和机会，来吸引参与者。技术总结该项目的主要目标是建立钼/铅硫化物量子点介晶的基本合成/结构关系，该项目由材料研究部的固体和材料化学计划支持。介晶被定义为在其超晶格位置上排列有高度平移和取向有序度的较小组成晶体的集合。胶体量子点(QD)构建块具有精确定义的尺寸、形状和组成，以及在理解和控制定向组装和附着方面的同步进展，使得QD介晶研究取得了显著进展。目前可用的量子点介晶仅限于单组分结构，但孤立量子点的科学技术发展告诉我们，从单组分异质结构向多组分异质结构(如核-壳或Janus-like)的转变引入了高级和可编程的功能。PI已经确定了异质结构量子点介晶的合成和分析是一项具有科学意义和技术重要性的研究挑战。PI接受了建立工艺/结构关系的挑战，将其作为紧密结合合成、组装和材料表征的机会。该提议提出了一种假设驱动的方法，具有三个互补的目标，专注于形成小平面特定的PBX-(MoS_2)m失配层异质结构，并将孤立的PBX-(MoS_2)m定向组装成一类新的超结构。这项拟议的研究提供了一个令人兴奋的机会，通过设计显着提高对具有性质的量子点介晶的知识。拟议研究的目标是雄心勃勃的，所产生的知识将显著促进对异质结构量子点介晶的基本理解、设计、可预测性和控制，具有令人信服的深远前景，未来在电催化和光电子学方面的进展。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical summaryWith this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, Professor Tobias Hanrath at Cornell University will explore the synthesis-structure relationships of a novel class of materials that combines nanoparticles with two-dimensional (2D) materials. By analogy to the rock-paper-scissors game, the investigators will use colloidal nanoparticles (i.e., rocks) to template the formation of molybdenum sulfide sheets (i.e., paper) on specific sections of the nanoparticle. Instead of scissors, the proposed synthesis approach leverages the well-defined nanoparticle shape (e.g., truncated cubes) to define the geometry of the particle-sheet composite. This project will have significant broader impact beyond the creation of new knowledge of scientific and societal importance, potentially leading to the development of new nanostructured composite materials with unique optical, electronic, and catalytic properties. Graduate students will receive extensive training and experience at the confluence of material fabrication and characterization approaches to investigate, understand and predict the formation of composite nanostructures. Outreach and education are closely integrated with the scientific work. The investigators will develop a ‘back-to-the-future’ workshop to engage participants by developing their vision for the future of their specific research field, the broader technological implications, and their personal roles and opportunities in bringing this future to fruition. Technical Summary The overarching objective of the proposed project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, is to establish the foundational synthesis/structure relationship of molybdenum/lead chalcogenide quantum dot mesocrystals. Mesocrystals are defined as assemblies of smaller constituent crystals arranged with high degree of translational and orientational ordering in their superlattice sites. Access to colloidal quantum dot (QD) building blocks with precisely defined size, shape, and composition as well as concurrent progress in understanding of and control over directed assembly and attachment have enabled remarkable advances in QD mesocrystals. Currently available QD mesocrystals are limited to single composition structures, yet the scientific and technological evolution of isolated QDs has taught us that moving from single-components to multi-composition heterostructures (e.g., core-shell or Janus-like) introduces advanced and programmable functionalities. The PI has identified the synthesis and analysis of heterostructured QD mesocrystals as a scientifically interesting and technologically important research challenge. The PI embraces the challenge of establishing processing/structure relationships as an opportunity to closely integrate synthesis, assembly, and materials characterization. The proposal presents a hypothesis-driven approach with three complementary objectives focused on formation of facet-specific PbX-(MoS2)m misfit layer heterostructures, and directed assembly of isolated PbX-(MoS2)m into a new class of superstructures. The proposed research presents an exciting opportunity to significantly improve upon the knowledge of QD mesocrystals with properties by design. The goals of the proposed research are ambitious, and the generated knowledge will significantly advance basic understanding, design, predictability and control over heterostructured QD mesocrystals with compelling far-reaching prospects for future advances in electrocatalysis and optoelectronicsThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.